(1) Field of the Invention
This invention generally relates to an attitude and roll stabilizer for towed undersea devices. More particularly, the invention relates to an attitude and roll stabilizer for towed undersea devices in which the undersea devices may be towed at varying speeds.
(2) Description of the Prior Art
The current art for attitude and roll stabilization of underwater vehicles has not in the past been directed to towing of the underwater device at varying speeds while controlling roll and pitch in an economical manner. Thus, a problem exists in the art whereby there is a need to control the roll and pitch of underwater vehicles being towed at varying speeds. The following patents, for example, disclose various types of deflectors for underwater vehicle control, but do not disclose a complete similarity with either the hardware or function of the attitude and roll stabilizer for towed undersea devices as set forth in connection with the disclosure of the present invention.
U.S. Pat. No. 5,357,892 to Vatne et al.;
U.S. Pat. No. 4,991,534 to Warman et al.;
U.S. Pat. No. 4,843,996 to Darche; and
U.S. Pat. No. 3,460,384 to Fohl.
Vatne et al. disclose a deflector for installation in the tow line between a towing vessel and a tow which is located in the water. A cable with seismic sources, or a seismic source array, is suspended by a float and has a fitting therefrom having a tow-point near the front part of the deflector connected to the tow line, and an attachment point to the rear of the deflector-for further connection thereto for the rear part of the tow line connected to the two. In order to be able to locate the deflector in a desired position in relation to the towing vessel and compensate for alternations in the effects of forces from the tow or vessel in addition to movements in the water, the tow line which leads on to the actual tow from the deflector body is attached to the deflector via a pivotable lever which is situated at the same height as the lifting force center of the deflector body. The tow point of the tow line body is provided at one lateral surface of the deflector body in front of the vertical center line thereof. An additional deflector wing may be incorporated in the rear part of the tow line. Accordingly, Vatne et al. describe a deflective device with the primary function of avoiding towing an object or different types of equipment directly behind the towing vessel. This device is very different in both hardware and function and, unlike the attitude and roll stabilizer for towed undersea devices of the present invention, it appears to be limited to shallow depth applications. Also, unlike the attitude and roll stabilizer for towed undersea devices according to the present invention, this prior art has no opportunity for electronic control.
The patent to Warman et al. discloses a depressor designed to keep a fish, towed by a ship, submerged and includes a flat swept wing joined to the towing cable by means of three suspenders making it possible to set it as an optimal angle of incidence. This enables a fish to be towed at a high speed which may go up to 30 knots while, at the same time, keeping it at a substantially constant depth of submersion. Accordingly, the device of Warman et al. is very different in both design and function and, unlike the attitude and roll stabilizer for towed undersea devices, does not provide roll stability to the towed device. Also, there is no electronic control capability.
The patent to Darche discloses a system, which is of the type comprising at the end of a primary cable, a first fish to which is connected a secondary cable towed by a second fish. There are provided, in proximity to the first fish, apparatus for measuring the angle between the direction of the relative current and the vertical plane passing through the secondary cable, and apparatus for measuring the angle of inclination of the secondary cable to the horizontal, connected to apparatus for automatically steering the second fish so as to bring the angles to predetermined values. Accordingly, Darche is simply directed to a device that maintains depth control of submerged devices that principally deploy forward of the tow surface craft. This device employs a forward and aft fish. The stability of the forward fish is dependent upon a propulsive capability of such forward fish, which derives electronic control from the aft fish. This device is very different in both design and function and, unlike the attitude and roll stabilizer for towed undersea devices according to the present invention, does not couple roll stability to the device under tow.
Fohl describes a mechanical depth-controlling device that is towed by a surface ship. In particular, the depth control device includes an adjustable boundary layer control coating with a liquid contacting surface of the structure. This device is very different in both hardware and function and, unlike the attitude and roll stabilizer for towed undersea devices of the present invention, does not couple roll stability to the device under tow. Furthermore, maintaining depth with any degree of accuracy appears to be difficult as the speed varies.
Accordingly, this invention is the result of being posed with the problem of using a surface craft to tow an underwater device at varying speeds and to stabilize the device in roll and pitch by the most economical means. This invention replaces the need for a complex and expensive stabilization control system.
It should be understood that the present invention would in fact enhance the functionality of the above patents by providing pitch and roll stabilization for underwater vehicles towed at varying speeds in a manner not previously known in the art.